Chemicals Made by Body May Strongly Suppress AIDS Virus

By David Brown
THE WASHINGTON POST
-- A group of chemicals made by cells and known for years to function as homegrown antibiotics may also be able to powerfully suppress growth of the AIDS virus, according to new research.

The inborn ability to produce larger-than-usual amounts of the substances may help explain why a few people infected with the AIDS virus can live for decades with no damage to their immune systems. Uncovering the biological secrets of those survivors is a major goal in AIDS research, as they may provide new strategies for treating or preventing the infection.

The researchers involved in the new work also believe the findings reveal the identity of a life-sustaining substance whose existence was first proposed in 1986, soon after the dawn of AIDS research. Named CAF for “CD8 antiviral factor,” the compound has long eluded scientists.

“It is gratifying to solve, to a large extent, a question that has been in the field for a long time,” said David Ho of the Aaron Diamond AIDS Research Center, who led the work that was done primarily by Linqi Zhang.

But CAF’s “discoverer,” Jay Levy of the University of California at San Francisco, doubts Ho has discovered his compound.

Ho and his colleagues wrote in an article published in Friday’s issue of Science that three related compounds, known as alpha-defensins 1, 2, and 3, are produced by immune system cells called CD8 lymphocytes, key cells in the body’s defense against HIV.

Defensins are one of the weapons of “innate” immunity, the ancient biological armament that attacks many forms of microbial invader. Innate immunity doesn’t entail the elaborate work of identifying and processing that’s required to make microbe-specific weapons, such as antibodies and killer cells.

Defensins were discovered in 1985. They function as antibiotics, rupturing the cell walls of bacteria. Their main source is a white blood cell called a neutrophil whose main target is bacteria and parasites, not viruses.